docs: def update_max_progress(self):
          """
          Compute progress of tree and max progress of sub-trees (not recursive).
          
          """
          self.update_progress()
          if self.leafnode:
              self.max_leaf_progress = self.progress
          else:
              self.max_leaf_progress = max(self.lower.max_leaf_progress, self.greater.max_leaf_progress)